1. Technical Field
The present invention relates to a method for producing a thermoplastic resin foamed blow-molded article, especially a thermoplastic resin foamed blow-molded article employing a thermoplastic resin composition containing a mixed resin of a polyphenylene ether resin and a polystyrene resin, as a base resin; and a thermoplastic resin foamed blow-molded article employing a thermoplastic resin composition containing a mixed resin of a polyphenylene ether resin and a polystyrene resin, as a base resin.
2. Related Art
A thermoplastic resin containing a mixed resin of a polyphenylene ether resin and a polystyrene resin (hereinafter, also referred to as a modified polyphenylene ether resin) is characterized in that the heat resistance is high, balance of the mechanical strength is excellent, and further a flame retardant treatment is readily performed. Therefore, taking advantage of these characteristics, the thermoplastic resin has been used in a wide variety of fields of housing of an electric equipment, automobile parts, and the like.
Conventionally, as this modified polyphenylene ether resin foam, for example, a foamed particle molded article produced by a so-called in-mold molding method in which resin particles are prepared by employing a mixed resin of a polyphenylene ether resin and a polystyrene resin, as a base resin, and foamable resin particles obtained by containing a blowing agent into the resin particles, or foamed particles obtained by foaming the foamable resin particles are filled in a cavity of the mold to be molded, has been known (for example, Japanese Patent Application Laid-Open (JP-A) No. S52-101268, and Japanese Patent No. 4712914).
Further, a sheet that is produced by kneading a mixed resin of a polyphenylene ether resin and a polystyrene resin, and a physical blowing agent to perform extrusion foaming, and then collecting the resultant along a cooling device such as a sizing drum, has been known (for example, JP-A No. H02-218727).
On the other hand, as a production method of a foamed molded article, there is a method in which a foamable molten resin obtained by kneading a thermoplastic resin and a blowing agent is extruded to forma foamed parison, and then the foamed parison is blow molded during being in a softened state to produce a foamed blow-molded article. By using the foaming blow-molding method, since a hollow molded article with an atypical shape can be produced in one step process, a foamed blow-molded article obtained by employing a polypropylene resin as abase resin is, taking advantage of features of the lightness and the thermal insulation, used for a duct for automotive air conditioner, and the like (for example, Japanese Patent No. 3745960).
In a thermoplastic resin foam composed of a polyphenylene ether resin and a polystyrene resin, an extrusion foam in which a phosphorus type compound, a compound having a triazine skeleton, and polyhydric alcohols are contained into the thermoplastic resin, and melting deformation and melting dripping during combustion are improved, has been disclosed (for example, JP-A No. 2003-138051).
However, it is difficult to produce a hollow foamed blow-molded article employing a thermoplastic resin composition containing a mixed resin of a polyphenylene ether resin and a polystyrene resin, as a base resin, by a foaming blow-molding method, and thus the foaming blow-molding method has not been practically industrially performed in the past.
The present invention relates to a method for producing a hollow foamed blow-molded article, and an object of the present invention is to provide a hollow foamed blow-molded article that employs a thermoplastic resin composition containing a mixed resin of a polyphenylene ether resin and a polystyrene resin, as a base resin, has a low apparent density and heat resistance, and is highly expanded; and a production method thereof.